SEMICONDUCTOR SUBSTRATE AND SEMICONDUCTOR ELEMENT

摘要

The present invention provides: a semiconductor substrate which is capable of improving the controllability of threshold voltage by the substrate bias and the controllability of gate electrode with respect to the potential of the channel region; and a semiconductor element which uses this substrate. The present invention is a semiconductor substrate which is used for the formation of a semiconductor element, and which is provided with: a supporting substrate (1); a buried insulating film (2) that is formed in contact with one main surface of the supporting substrate (1); and a semiconductor layer (5) that is formed in contact with the buried insulating film (2) on a surface that is on the reverse side of the supporting substrate (1)-side surface, said semiconductor layer (5) having a film thickness thinner than that of the supporting substrate (1). The dielectric constant of the buried insulating film (2) in a region that is in contact with the semiconductor layer (5) is lower than the dielectric constant of the buried insulating film (2) in a region that is in contact with the supporting substrate (1).